Electromagnetic Design of a High-Speed Solid Cylindrical Permanent-Magnet Motor Equipped With Active Magnetic Bearings

This paper presents the design in electromagnetic aspect of a high-speed solid cylindrical permanent-magnet (PM) machine equipped with magnetic bearings. First, the selection of PM machine structures is discussed. In specific, the analytical models of magnetic field for the solid cylindrical PM machine and ring PM machine are established; then, these two machine configurations are compared from the perspectives of magnetic design and rotor eddy-current losses, and the results show that the solid cylindrical PM machines have higher power density and lesser rotor eddy-current losses than ring PM machines. Subsequently, the rotor structures are described, and some integrated considerations in design of high-speed PM machines equipped with magnetic bearings are pointed out. Then, the configurations of magnetic bearings used for the machines are determined, and their analytical formulas of magnetic force are deduced. Ultimately, a 30 kW 60 000 r/min high-speed solid cylindrical PM motor equipped with magnetic bearings is designed and manufactured, and serial experimental tests are conducted on this prototype to verify the theoretical design and the practical performance of the machine.